Arthur and Hoi-way: VIOLET RUSTS OF NORTH AMERICA. 633 



occurs in open woodlands from the last of March to the begin- 

 ning of June, but is rather infrequent and local. It is distin- 

 gished from the secidium of Puccinia Violce by the markedly 

 smaller cups and spores, and by a greater tendency to form 

 small, round groups seated on the mesophyll of the blade, 

 rather than on the midrib or veins. The peridium is usually 

 conspicuously white ; the cylindrical elongation noted in the 

 description by Berkeley and Curtis is occasionally to be seen, 

 but must be considered as accidental, depending upon condi- 

 tions of growth. The same kind of development is met with 

 in other forms of gecidia (see notes on J&cidium -pulcherrimum 

 Rav. in Bull. Lab. Nat. Hist, of Univ. Iowa 4: 399-400). 



Examination of specimens in the Schweinitz collection at the 

 herbarium of the Philadelphia Academy of Sciences shows that 

 both species which he described as new, occurring on Viola 

 pcdata and V. sagittata respectively, belong here. The name 

 coming first on the page is taken as the authentic name of the 

 species. The Schweinitz specimens on both hosts are ample, 

 but neither shows the Eecidia in so characteristic a form as does 

 the specimen in the same collection on Viola obliqua, which 

 Schweinitz referred to sEcidium Violarum. The last has very 

 small, compactly clustered aecidial cups, in small round groups, 

 while both the former have the cups somewhat larger, and 

 sparsely scattered or solitary. The difference in habit is doubt- 

 less due to the influence of the host and the atmospheric con- 

 ditions affecting the development, in part, combined with the 

 accidental distribution of the infection over the leaf surface. 



Spermogonia have not been seen by the writers, but Burrill 

 (Par. Fung. 111., p. 223) states that they precede the secidia, al- 

 though he does not describe them. 



Puccinia Violas (SCHUM.) DC. 1815. Flore Francaise 6:62. 

 SYN. : 



1803. jEcidium Viola SCHUM. Fl. Saell. 2: 224. 

 1803. Uredo Viola SCHUM. Fl. Saell. 2: 233. 

 1805. ^Ecidium Violarum DC. Fl. Franc. 2: 240. 

 1825. Puccinia Violarum LINK. Sp. Plant. 2: 80. 

 1875. Puccinia hastatce COOKE, Grev. 3: 179. 

 1888. Puccinia Fergussoni hastatce DsT. Sacc. Syll. 

 Fung. 7: 682. 



1897. Puccinia densa D. & H. Hedw. 26: 298. 



1898. Dicceoma Violce KUNTZE, Rev. Gen. PL 3: 471. 



